1. Field of the Invention
The present invention relates to an outboard drive of a watercraft, and in particular to an electronic control unit for a trim and trim system associated with an outboard drive, such as, for example an outboard motor.
2. Description of Related Art
The desirable trim angle of an outboard drive varies with a watercraft's running condition. For instance, the bow of the watercraft should press against the water when accelerating from rest or from a slow speed. To achieve this condition, the angle of the propeller shaft is disposed at a negative angle relative to the horizontal (i.e., at a negative trim angle). A thrust vector produced by the propeller in this position is thus out of the water. When running at high speed, the propeller is raised or trimmed to position the propeller shaft at a positive trim angle relative to the horizontal within the range of about 0.degree. to 15.degree..
A hydraulic tilt and trim system often supports and adjusts the trim position of a large outboard motor (e.g., 150 hp or greater). The tilt and trim system includes hydraulic actuators that operate between a clamping bracket, which is attached to the watercraft, and a swivel bracket that supports the outboard motor. A pivot pin connects the swivel and clamping brackets together. The actuators cause the swivel bracket to pivot about the axis of the pivot pin relative to the stationary clamping bracket.
At least one fluid motor powers the actuators. The fluid motor includes a pump that pressurizes hydraulic fluid within the lines of the system. Various valves control the delivery of the pressurized fluid to the actuators. A reversible electric motor desirably drives the pump. By reversing the direction in which the pump is run, the actuators are either extended or retracted in order to raise or lower the outboard drive, respectively.
The actuators and fluid motor, as well as a reservoir in communication with the fluid motor, are positioned beneath the power head of the outboard motor. In many applications, these components lie generally between the swivel bracket and the clamping bracket.
A controller usually controls the operation of the fluid motor to control the reversible pump motor. The controller often employs relays within it circuitry to switch the direction of the pump motor. These electrical components are potted in order to shield and seal them from water and dirt.
While prior controllers are effective in performing this function, they often are difficult and costly to assemble. In addition, some controllers do not provide adequate protection of the components and circuitry. The resulting corrosion and dirt interfere with the proper functioning of the controller.